(PHP 4 )
array_intersect -- Computes the intersection of arrays
Description
array 
array_intersect ( array array1, array array2 [, array ...])
     array_intersect() returns an array
     containing all the values of array1
     that are present in all the arguments.
     Note that keys are preserved.
    
     
| Example 1. array_intersect() example | $array1 = array ("a" => "green", "red", "blue");
$array2 = array ("b" => "green", "yellow", "red");
$result = array_intersect ($array1, $array2); | 
 
       This makes $result have
        | Array
(
    [a] => green
    [0] => red
) | 
 | 
    Note: 
      Two elements are considered equal if and only if
      (string) $elem1 === (string) $elem2. In words:
      when the string representation is the same.
      
     
| Warning | 
| 
      This was broken in PHP 4.0.4!
      
      | 
     See also array_diff().